RC-6 is part of the International Mobile Identification (IMI) mobile identification system. It is a truncated version of the original RC-6 standard used for online authentication. The system is based on a challenge-response protocol that requires users to generate a unique response key based on a preset secret key and a challenge value sent by the verifying system. The secret key used in the process is embedded in the IMI mobile wallet and is not exposed to the user. Through this process, users can authenticate their identity when requested by a verifying system. The RC-6 protocol is more secure than other two-factor authentication methods and is recommended for group and individual authentication.